Add carriage return at EBCDIC file

I used IO.StreamReader and IO.StreamWriter to read EBCDIC and write to text file learning from below:
http://www.codeproject.com/Articles/31720/How-to-Read-an-EBCDIC-File-in-VB-NET
It works fine.
How can I add carriage return at col 500? (EBCDIC file has 1500 col and 50000 line)